Seatbelt retractor, seatbelt apparatus, and vehicle with a seatbelt apparatus

ABSTRACT

A retractor of a seatbelt apparatus to be installed in a vehicle is structured such that a motor is accommodated in a hollow cylindrical space of a spool and such that the size of a motor housing of the motor in the axial direction and the size of a spool outer periphery of the spool in the width direction are substantially equal to each other.

BACKGROUND

The present invention relates to a technology for developing a seatbeltretractor to be installed in a vehicle.

Conventionally, a seatbelt apparatus is known, which is structured toprotect an occupant in a vehicle by a seatbelt (webbing) restraining theoccupant. For example, PCT international application No. 2003-507252(hereby incorporated by reference herein in its entirety) discloses astructure of a seatbelt retractor of a seatbelt apparatus, in which aspool (winding shaft) can be rotated in a belt-winding direction or abelt-unwinding direction for a seatbelt by an electric motor.

SUMMARY

One embodiment of the invention relates to a seatbelt retractor. Theseatbelt retractor comprises a spool formed into a hollow cylindricalshape and capable of winding a seatbelt onto a spool outer periphery orunwinding the seatbelt from the spool outer periphery, wherein theseatbelt is adapted to be worn by a vehicle occupant seated in a seat; amotor accommodated in a hollow space of the spool and configured torotate the spool in the belt winding direction or the belt unwindingdirection; a motor speed-reduction mechanism configured to reduce therotational speed of the motor via a plurality of gears between thedriving shaft of the motor and the spool; and a control mechanismconfigured to control the operation of the motor. In the state that themotor is accommodated in the hollow space, a motor housing of the motorextends along the width direction of the spool outer periphery of thespool such that the axial direction of the motor coincides with thewidth direction of the spool outer periphery. The length of the motorhousing in the axial direction and the width of the spool outerperiphery are substantially equal.

Another embodiment of the invention relates to a seatbelt retractor. Theseatbelt retractor comprises a spool formed into a hollow cylindricalshape and capable of winding a seatbelt onto a spool outer periphery orunwinding the seatbelt from the spool outer periphery, wherein theseatbelt is adapted to be worn by a vehicle occupant seated in a seat; amotor accommodated in a hollow space of the spool and configured torotate the spool in the belt winding direction or the belt unwindingdirection; a motor speed-reduction mechanism configured to reduce therotational speed of the motor via a plurality of gears between the shaftof the motor and the spool; and a control mechanism configured tocontrol the operation of the motor. In the state that the motor isaccommodated in the hollow space, a motor housing of the motor extendsalong the width direction of the spool outer periphery of the spool suchthat the axial direction of the motor housing coincides with the widthdirection of the spool outer periphery, and the motor speed-reductionmechanism is disposed adjacent to the motor housing relative to theaxial direction of the motor housing. A first length relating to thewidth direction of the spool outer periphery and a second lengthcorresponding to the length of the motor housing in the axial directionplus a length of the motor speed-reduction mechanism in the axialdirection are substantially equal.

Another embodiment relates to a seatbelt apparatus. The seatbeltapparatus comprises a seatbelt retractor; and a seatbelt to be worn by avehicle occupant seated in a seat. The seatbelt retractor comprises aspool formed into a hollow cylindrical shape and capable of winding theseatbelt onto a spool outer periphery or unwinding the seatbelt from thespool outer periphery; a motor accommodated in a hollow space of thespool and configured to rotate the spool in the belt winding directionor the belt unwinding direction; a motor speed-reduction mechanismconfigured to reduce the rotational speed of the motor via a pluralityof gears between the driving shaft of the motor and the spool; and acontrol mechanism configured to control the operation of the motor. Inthe state that the motor is accommodated in the hollow space, a motorhousing of the motor extends along the width direction of the spoolouter periphery of the spool such that the axial direction of the motorcoincides with the width direction of the spool outer periphery. Thelength of the motor housing in the axial direction and the width of thespool outer periphery are substantially equal.

Another embodiment of the invention relates to a seatbelt apparatus. Theseatbelt apparatus comprises a seatbelt retractor; and a seatbelt to beworn by a vehicle occupant seated in a seat. The seatbelt retractorcomprises a spool formed into a hollow cylindrical shape and capable ofwinding the seatbelt onto a spool outer periphery or unwinding theseatbelt from the spool outer periphery; a motor accommodated in ahollow space of the spool and configured to rotate the spool in the beltwinding direction or the belt unwinding direction; a motorspeed-reduction mechanism configured to reduce the rotational speed ofthe motor via a plurality of gears between the shaft of the motor andthe spool; and a control mechanism configured to control the operationof the motor. In the state that the motor is accommodated in the hollowspace, a motor housing of the motor extends along the width direction ofthe spool outer periphery of the spool such that the axial direction ofthe motor housing coincides with the width direction of the spool outerperiphery, and the motor speed-reduction mechanism is disposed adjacentto the motor housing relative to the axial direction of the motorhousing. A first length corresponding to the width of the spool outerperiphery and a second length corresponding to the length of the motorhousing in the axial direction plus a size relating to the axialdirection of the motor speed-reduction mechanism are substantiallyequal.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory only,and are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become apparent from the following description, appendedclaims, and the accompanying exemplary embodiments shown in thedrawings, which are briefly described below.

FIG. 1 shows a schematic structure of a seatbelt apparatus 100, which isinstalled in a vehicle, of an embodiment according to the presentinvention.

FIG. 2 is a sectional view of a retractor 130 shown in FIG. 1.

FIG. 3 is a sectional view on arrows of a line A-A of the retractor 130shown in FIG. 2.

DETAILED DESCRIPTION

The technology described in PCT international application No.2003-507252 gives us a possibility of using an electric motor to conductthe action of the spool for winding or unwinding the seatbelt, as astructure of the seatbelt retractor. With regard to the design of suchseatbelt apparatuses, further technical requirement exists for reducingthe size of the seatbelt retractor to correspond to the configuration ofa pillar or the like as a narrow space for accommodating the seatbeltretractor.

Therefore, embodiments of the present invention have been made in viewof the above requirement and it is an object of the present invention toprovide a technology effective for the miniaturization of a seatbeltretractor to be installed in a vehicle.

For achieving the object, the present invention is made. The presentinvention can be typically adapted to a seatbelt retractor to beinstalled in an automobile. The present invention can be applied to atechnology for a seatbelt retractor to be installed in a vehicle otherthan the automobile.

The seatbelt retractor according to a first embodiment comprises atleast a spool, a motor, a motor speed-reduction mechanism, and a controlmechanism.

The spool of this embodiment is a member which is formed into a hollowcylindrical shape and is capable of winding a seatbelt onto a spoolouter periphery thereof or unwinding the seatbelt from the spool outerperiphery. The spool outer periphery is adapted to be a surface withwhich the seatbelt is in contact. The seatbelt is a long belt to be wornby a vehicle occupant seated in a seat and is sometimes called“webbing”. Typically, the vehicle occupant seated in the vehicle seat isrestrained by the seatbelt when restraint is required such as a vehiclecollision, thereby ensuring the protection of the vehicle occupant.

The motor of this embodiment is accommodated in the hollow space of thespool and has a function of rotating the spool in the belt windingdirection or the belt unwinding direction.

The motor speed-reduction mechanism has a function of reducing therotational speed of the motor via a plurality of gears between thedriving shaft of the motor and the spool.

The control mechanism of this embodiment is a mechanism for controllingthe operation (the rotational speed, the rotational direction) of themotor. The control mechanism is typically composed of a CPU (centralprocessing unit), an input/output unit, a storage unit, a peripheralunit, and the like.

According to this embodiment, in the state that the motor isaccommodated, a motor housing of the motor extends along the widthdirection of the spool outer periphery of the spool such that the axialdirection of the motor coincides with the width direction of the spoolouter periphery, and the size of the motor housing in the axialdirection and the size of the spool outer periphery in the widthdirection are substantially equal to each other. According to thisstructure, the width of the spool is reduced to correspond to the sizeof the motor housing in the axial direction, thereby reducing theoverall size relating to the axial direction of the seatbelt retractor.Therefore, the reduction in size of the seatbelt retractor to beinstalled in the vehicle is achieved, thereby increasing the degree offreedom of location of the seatbelt retractor in the vehicle. Theoverall size of the spool in the width direction is generally largerthan the size of the spool outer periphery in the width direction.However, when the overall size of the spool in the width direction issubstantially the same as the size of the spool outer periphery in thewidth direction, the size of the motor housing in the axial direction issubstantially equal to not only the size of the spool outer periphery inthe width direction but also the overall size of the spool in the widthdirection.

According to the structure of this embodiment in which the motor isaccommodated in the hollow space of the spool, the reduction in size andthe reduction in weight of the seatbelt retractor are achieved and, inaddition, the noise insulation and the electromagnetic-wave shielding inthe operation of the motor are improved.

According to the structure of this embodiment in which the spool isrotated by the motor, a spring mechanism for biasing the spool in thebelt winding direction can be eliminated. The spring mechanism isgenerally located adjacent to the spool in the width direction of thespool. Therefore, the elimination of the spring mechanism reduces thesize relating to the width direction of the spool, thereby enabling thefurther reduction in overall size of the seatbelt retractor.

The seatbelt retractor according to a second embodiment is adapted suchthat the size of the motor housing in the axial direction and the sizeof the spool outer periphery in the width direction are alsosubstantially equal to the width of the seatbelt. That is, in thisembodiment, the size of the motor housing in the axial direction and thesize of the spool outer periphery in the width direction are set tocorrespond to the standard width of the seatbelt. According to thisstructure, the overall size relating to the axial direction of theseatbelt retractor can be reduced, thereby achieving the furtherreduction in size of the seatbelt retractor to be installed in thevehicle. The motor housing is designed to have the maximum size in theaxial direction within the range of the width of the spool, allowing theuse of a motor with higher output.

The seatbelt retractor according to a third embodiment comprises atleast a spool, a motor, a motor speed-reduction mechanism, and a controlmechanism, substantially similar to the seatbelt retractor of the firstembodiment.

According to this embodiment, in the state that the motor isaccommodated, a motor housing of the motor extends along the widthdirection of the spool outer periphery of the spool such that the axialdirection of the motor housing coincides with the width direction of thespool outer periphery, and the motor speed-reduction mechanism isdisposed adjacent to the motor housing in the axial direction of themotor housing. In addition, according to this invention, a first sizerelating to the width direction of the spool outer periphery and asecond size which is the size relating to the axial direction of themotor housing plus the size relating to the axial direction of the motorspeed-reduction mechanism are substantially equal to each other.According to this structure, the width of the spool is reduced tocorrespond to the size of a combination of the motor housing and themotor speed-reduction mechanism in the axial direction. Therefore, thereduction in overall size of the seatbelt retractor to be installed inthe vehicle is achieved, thereby increasing the degree of freedom oflocation of the seatbelt retractor in the vehicle. The overall size ofthe spool in the width direction is generally larger than the size ofthe spool outer periphery in the width direction. However, when theoverall size of the spool in the width direction is substantially thesame as the size of the spool outer periphery in the width direction,the second size which is the size relating to the axial direction of themotor housing plus the size relating to the axial direction of the motorspeed-reduction mechanism is substantially equal to not only the firstsize of the spool outer periphery in the width direction but also theoverall size of the spool in the width direction.

According to the structure of this embodiment in which the motor isaccommodated in the hollow space of the spool, the reduction in size andthe reduction in weight of the seatbelt retractor are achieved and, inaddition, the noise insulation and the electromagnetic-wave shielding inthe operation of the motor are improved.

According to the structure of this embodiment in which the spool isrotated by the motor, a spring mechanism for biasing the spool in thebelt winding direction can be eliminated. The spring mechanism isgenerally located adjacent to the spool in the width direction of thespool. Therefore, the elimination of the spring mechanism reduces thesize relating to the width direction of the spool, thereby enabling thefurther reduction in overall size of the seatbelt retractor.

The seatbelt retractor of a fourth embodiment has the same or similarstructure as the third embodiment and is adapted such that the firstsize and the second size are also substantially equal to the width ofthe seatbelt. That is, in this embodiment, the first size relating tothe width direction of the spool outer periphery and the second sizewhich is the size relating to the axial direction of the motor housingplus the size relating to the axial direction of the motorspeed-reduction mechanism are set to correspond to the standard width ofthe seatbelt. According to this structure, the overall size relating tothe axial direction of the seatbelt retractor can be reduced, therebyachieving the further reduction in size of the seatbelt retractor to beinstalled in the vehicle. The motor housing is designed to have themaximum size in the axial direction within the range of the width of thespool, allowing the use of a motor with higher output.

The seatbelt retractor according to a fifth embodiment has the same orsimilar structure as the third or fourth embodiments and is adapted suchthat the gears of the motor speed-reduction mechanism are arranged toextend on the same plane perpendicular to the axial direction of themotor housing. According to this structure, the size relating to theaxial direction of the motor speed-reduction mechanism can be reduced byarrangement of the plural gears, thereby further reducing the overallsize relating to the axial direction of the retractor including themotor speed-reduction mechanism. Therefore, the further reduction insize of the seatbelt retractor to be installed in the vehicle isachieved.

The seatbelt retractor of a sixth embodiment has the same or similarstructure as in any one of the above embodiments and is adapted suchthat the spool and the motor housing are supported by each other atleast via a bearing mechanism disposed between the inner periphery ofthe spool and the outer periphery of the motor housing. For composingthe suitable bearing structure, the present embodiment allows theadoption of another bearing mechanism in addition to the bearingmechanism disposed between the inner periphery of the spool and theouter periphery of the motor housing, if necessary. According to thisstructure, the rotation of the spool relative to the motor housing isallowed by the bearing structure with simple structure.

The seatbelt retractor according to a seventh embodiment has the same orsimilar structure as in any one of the above embodiments and is adaptedto be accommodated in an accommodating space in a rear pillar of anautomobile which is located on the rear side of the A-pillar of theautomobile. The “rear pillar” used here corresponds to a B-pillar or aC-pillar in case of an automobile having two rows of seats orcorresponds to a B-pillar, a C-pillar, or a D-pillar in case of anautomobile having three rows of seats. This structure enables to providea compact seatbelt retractor which can be accommodated in theaccommodating space of the rear pillar of which size is limited.

The seatbelt retractor of an eighth embodiment has the same or similarstructure as in any one of the above embodiments and is adapted to beaccommodated in an accommodating space in a seat of an automobile. The“seat” used here widely includes a driver's seat and a passenger's seatin a first-row, and second- and third-row seats. This structure enablesto provide a compact seatbelt retractor which can be accommodated in theaccommodating space of the seat of which size is limited.

The seatbelt retractor according to a ninth embodiment has the same orsimilar structure as in the seventh or eighth embodiments and is adaptedsuch that, in the state that the seatbelt retractor is accommodated inthe accommodating space, the spool outer periphery of the spool extendsin the longitudinal direction of a vehicle, and the size of the spoolouter periphery in the width direction and the size of the accommodatingspace in the rear pillar or the accommodating space in the seat in thelongitudinal direction of the vehicle are substantially equal to eachother. This structure enables to provide a compact seatbelt retractorwhich can be accommodated in the accommodating space in the rear pillarof which size is limited in the longitudinal direction of the vehicle orin the accommodating space of the seat of which size is limited.

The seatbelt apparatus of a tenth embodiment is a seatbelt apparatuscomprising at least a seatbelt retractor as in any one of the aboveembodiments, and a seatbelt to be worn by a vehicle occupant seated in aseat and which can be wound onto or unwound from a spool outer peripheryof a spool of the seatbelt retractor.

According to this structure, the width of the spool is reduced tocorrespond to the size of the motor housing in the axial direction,thereby reducing the overall size relating to the axial direction of theseatbelt retractor. Therefore, the reduction in size of the seatbeltapparatus to be installed in the vehicle is achieved, thereby increasingthe degree of freedom of location of the seatbelt apparatus in thevehicle.

The vehicle with a seatbelt apparatus according to an eleventhembodiment is a vehicle in which the seatbelt apparatus is the same orsimilar to any one of the above embodiments and is accommodated in anaccommodating space in a pillar or an accommodating space in a seat.This structure enables to provide a vehicle in which a miniaturizedseatbelt apparatus is accommodated in an accommodating space in a pillarof the vehicle or in an accommodating space in a seat of the vehicle.

As described in the above, the present embodiment can provide atechnology, particularly relating to the structure of a seatbeltretractor, that is effective for the reduction in size of the seatbeltretractor to be installed in a vehicle by designing such that the sizeof a motor housing in the axial direction and the size of the outerperiphery of a spool in the width direction are substantially equal toeach other.

Hereinafter, embodiments of the present invention will be described indetail with reference to drawings. First, description will be made asregard to the structure of a seatbelt apparatus 100 as one ofembodiments of “seatbelt apparatus” according to the present inventionwith reference to FIG. 1 through FIG. 3.

The schematic structure of the seatbelt apparatus 100, which isinstalled in a vehicle, of the embodiment according to the presentinvention is shown in FIG. 1.

As shown in FIG. 1, the seatbelt apparatus 100 of this embodiment is aseatbelt apparatus for a vehicle to be installed in an automotivevehicle as “a vehicle with a seatbelt apparatus” and mainly consists ofa seatbelt 110, a retractor 130, and an ECU 150. In addition, an inputelement 170 is installed in the vehicle to detect information aboutcollision prediction or collision occurrence of the vehicle, informationabout the driving state of the vehicle, information about the sittingposition and the body size of a vehicle occupant seated in a vehicleseat, information about traffic conditions around the vehicle,information about weather condition and about time zone, and the likeand to input such detected information to the ECU 150. The detectedinformation of the input element 170 is transmitted to the ECU 150anytime or at predetermined intervals and is used for the operationcontrol of the seatbelt apparatus 100 and the like.

The seatbelt 110 is a long belt (webbing) to be used for restraining avehicle occupant C seated in a vehicle seat 10 as a driver's seat(corresponding to the “seat” of the present invention). The seatbelt 110is withdrawn from the retractor 130 fixed to the vehicle and extendsthrough a deflection fitting 111 provided around an area about theshoulder of the vehicle occupant C and is connected to an outer anchor114 through a tongue 112. The deflection fitting 111 has a function ofholding the seatbelt 110 to the area about the shoulder of the occupantC and guiding the seatbelt 110. By inserting the tongue 112 to a buckle116 fixed to the vehicle body, the seatbelt 110 becomes into the stateworn by the vehicle occupant C. The seatbelt 110 corresponds to the“seatbelt” of the present invention.

The retractor 130 is a device capable of performing the action ofwinding or unwinding the seatbelt 110 by a spool 132 as will bedescribed later and corresponds to the “seatbelt retractor” of thepresent invention. The retractor 130 is installed in an accommodatingspace in a B-pillar 12 of the vehicle in the embodiment shown in FIG. 1.

The ECU 150 has a function of conducting the control of the retractor130 and other operational mechanisms based on the input signals from theinput element 170 and comprises a CPU (Central processing unit), aninput/output unit, a storage unit, a peripheral unit, and the like.Particularly in this embodiment, the ECU 150 controls a motor 133, aswill be described later, of the retractor 130. Specifically, the ECU 150controls the amount of current supplied to an electromagnetic coil ofthe motor 133 and the direction of the current so as to vary therotational speed or the rotational direction of a shaft of the motor133. The ECU 150 corresponds to the “control mechanism” of the presentinvention and the input element 170 for inputting input signals to theECU 150 corresponds to the “input element” of the present invention.

Referring to FIG. 2 and FIG. 3, the retractor 130 will be described indetail. FIG. 2 is a sectional view of the retractor 130 shown in FIG. 1and FIG. 3 is a sectional view on arrows of a line A-A of the retractor130 shown in FIG. 2.

As shown in FIG. 2, the retractor 130 of this embodiment comprises abase frame (retractor body frame) 131, which is fixed to the vehiclebody, and further comprises the spool (winding shaft) 132, the motor133, a Hall sensor 134, a magnetic disc 135, an internal gear 136,planetary gears 137, a sun gear 138, a carrier 139, and bearings 140,141 which are assembled inside the base frame 131.

The spool 132 of the retractor 130 is a member rotatably supported tothe base frame 131 and corresponds to the “spool” of the presentinvention. Specifically, the bearing 140 lies between the spool 132 andthe internal gear 136 which is a fixed member and the bearing 141 liesbetween the spool 132 and the body of the motor 133 which is a fixedmember, whereby the spool 132 is rotatable relative to the fixedmembers. That is, the spool 132 and a motor housing 133 a of the motor133 are supported by each other via the bearing mechanism (bearing 140)disposed between the outside surface of the spool and the inside surfaceof the internal gear and the bearing mechanism (bearing 141) disposedbetween the inner periphery of the spool and the outer periphery of themotor housing. According to this structure, the rotation of the spool132 relative to the motor housing 133 a is allowed by simple bearingstructure.

In the retractor 130, the seatbelt 110 is wound onto a spool outerperiphery 132 a of the spool 132 or the seatbelt 110 is unwound from thespool outer periphery 132 a of the spool 132. That is, the spool outerperiphery 132 a of the spool 132 is a surface with which the seatbelt110 is in contact. The shaft of the motor 133 is rotated in onedirection so as to conduct operation of unwinding the seatbelt from thespool 132, while the shaft of the motor 133 is rotated in the otherdirection so as to conduct operation of winding the seatbelt 110 ontothe spool 132. Details about this will be described later. According tothe structure of rotating the spool by the motor such as thisembodiment, a spring mechanism for biasing the spool 132 in the beltwinding direction can be eliminated. The spring mechanism is generallylocated adjacent to the spool in the width direction of the spool 132.Therefore, the elimination of the spring mechanism reduces the sizerelating to the width direction of the spool 132, thereby enabling thereduction in overall size of the retractor 130.

The spool 132 is formed into a hollow cylindrical shape of which one endis closed and the other end is open. The motor 133 is inserted into acylindrical hollow space 132 b through the open end and is accommodatedin the hollow space 132 b. In the state that the motor 133 isaccommodated in the hollow space 132 b of the spool 132, the motorhousing 133 a of the motor 133 extends along the width direction of thespool outer periphery 132 a of the spool 132 such that the axialdirection of the motor 133 coincides with the width direction of thespool outer periphery 132 a.

In the state that the motor 133 is accommodated, three dimensions, i.e.,the size L1 of the motor housing 133 a of the motor 133 in the axialdirection, the size L2 of the spool outer periphery 132 a of the spool132 in the width direction, and the width of the seatbelt 110 aresubstantially equal to each other. That is, in this embodiment, the sizeof the motor housing 133 a in the axial direction and the size of thespool outer periphery 132 a in the width direction are set to correspondto the standard width of the seatbelt 110. As shown in FIG. 2, in thisembodiment, the overall size of the spool 132 in the width direction isnearly equal to the size of the spool outer periphery 132 a in the widthdirection. That is, the four dimensions, i.e. the overall size of thespool 132 in the width direction, the size L1 of the motor housing 133 ain the axial direction, the size L2 of the spool outer periphery 132 ain the width direction, and the width of the seatbelt 110 aresubstantially equal to each other.

According to this structure, the width of the spool 132 can be reducedto correspond to the size of the motor housing 133 a in the axialdirection, thereby reducing the overall size relating to the axialdirection of the retractor 130. Therefore, the miniaturization of theretractor 130 and the seatbelt apparatus 100 to be installed in thevehicle is achieved, thereby increasing the degree of freedom oflocation of the seatbelt retractor 130 and the seatbelt apparatus 100 inthe vehicle. The motor housing 133 a is designed to have the maximumsize in the axial direction within the range of the width of the spool132, allowing the use of a motor with higher output.

According to the structure of this embodiment that the motor 133 isaccommodated in the cylindrical space of the spool 132, the reduction insize and the reduction in weight of the retractor 130 are achieved and,in addition, the noise insulation and the electromagnetic-wave shieldingin the operation of the motor are improved.

In this embodiment, it is preferable that the ratio of the outsidediameter D1 of the motor housing 133 a of the motor 133 relative to theoutside diameter D2 of the spool outer periphery 132 a of the spool 132,i.e. D1/D2, is set to be 0.8 or less. For example, the outside diameterD1 of the motor 133 may be 40 (mm) and the outside diameter D2 of thespool outer periphery 132 a of the spool 132 may be 55 (mm). Accordingto this structure, the size of the spool 132 in the radial direction canbe reduced to correspond to the size of the motor 133 in the radialdirection, thereby enabling the reduction in overall size relating tothe radial direction of the retractor 130.

The motor 133 of this embodiment is an electric motor of a type,so-called “brushless motor of inner rotor type”. The motor 133corresponds to the “motor” of the present invention. The motor 133 usesa magnet as a rotor and a coil as a stator which are accommodated in themotor housing 133 a. The stator is disposed around the rotor. The motor133 is structured such that the motor shaft is rotated according to therotation of the rotor. In the motor 133, the Hall sensor (a magneticposition detector) 134 is mounted on a side of the motor housing 133 aand the magnetic disc 135 is mounted on a side of the rotor. The Hallsensor 134 and the magnetic disc 135 cooperate together to detect theposition of the rotor. From the information of the detection, the amountof winding or unwinding the seatbelt 110 is obtained. Based on theamount of winding or unwinding of the seatbelt 110, the rotational speedof the motor and the load of the motor can be controlled. In thisembodiment, as mentioned above, the position detecting mechanism of therotor in the motor 133 is also used as a mechanism for detecting theamount of winding or unwinding the seatbelt 110. Therefore, the use ofthe blushless motor structured similarly to this motor 133 can eliminatesensors for exclusive use of detecting the rotational speed androtational direction of the rotor and of detecting the amount of windingor unwinding the seatbelt. This is economical. The blushless motorstructured similarly to the motor 133 is effective for reducing the sizeof the body, improving the output, and improving the heat radiationproperty.

As shown in FIG. 2 and FIG. 3, the shaft of the motor 133 is adapted tohave the sun gear 138. Three planetary gears 137 mesh with the outerperiphery of the sun gear 138. The outer peripheries of the planetarygears 137 mesh with inner periphery of the internal gear 136. That is, agear train, so-called “planetary gear mechanism” is constructed in whichthe planetary gears 137 are arranged between the internal gear 136 andthe sun gear 138. The internal gear 136 is fixed to the base frame 131.The planetary gears 137 are rotatably supported by the carrier 139 andthe spool 132 is connected to the carrier 139. The internal gear 136,the planetary gears 137, the sun gear 138 compose together aspeed-reduction mechanism (corresponding to the “motor speed-reductionmechanism” of the present invention) of the motor 133. In thisembodiment, the motor speed-reduction mechanism is located adjacent tothe motor housing 133 a relative to the axial direction of the motorhousing 133 a. Further in this embodiment, the plural gears composingthe motor speed-reduction mechanism are arranged to extend on the sameplane in a direction perpendicular to the axial direction of the shaftof the motor. According to the structure, the size relating to the axialdirection of the motor speed-reduction mechanism can be reduced byarrangement of the plural gears, thereby further reducing the overallsize relating to the axial direction of the retractor 130 including themotor speed-reduction mechanism. Therefore, the reduction in size of theretractor 130 and the seatbelt apparatus 100 to be installed in thevehicle is achieved.

In this embodiment, the three dimensions, i.e. the first size relatingto the width direction of the spool outer periphery 132 a, the secondsize which is the size relating to the axial direction of the motorhousing 133 a plus the size relating to the axial direction of the motorspeed-reduction mechanism, and the width of the seatbelt 110 aresubstantially equal to each other. That is, in this embodiment, thefirst size and the second size are set to correspond to the standardwidth of the seatbelt 110. As shown in FIG. 2, in this embodiment, theoverall size of the spool 132 in the width direction is nearly equal tothe size of the spool outer periphery 132 a in the width direction. Thatis, the four dimensions, i.e. the overall size of the spool 132 in thewidth direction, the first size, the second size, and the width of theseatbelt 110 are substantially equal to each other. According to thisstructure, the width of the spool 132 can be reduced to correspond tothe size of the combination of the motor housing 133 a with the motorspeed-reduction mechanism in the axial direction, thereby reducing theoverall size relating to the axial direction of the seatbelt retractor.

In this embodiment, the shaft as the rotational axis of the motor 133,the spool shaft as the rotational axis of the spool 132, thespeed-reduction shaft as the rotational axis of the sun gear 138 as onecomponent of the speed-reduction mechanism are generally aligned in astraight line. According to the structure, the simplification andminiaturization of the motor speed-reduction mechanism are achieved.

In the aforementioned structure of the retractor 130, as the shaft ofthe motor 133 is rotated, the three planetary gears 137 meshing with thesun gear 138 move around the speed-reduction shaft of the sun gear 138,whereby the spool 132 rotates via the carrier 139. For example, when thesun gear 138 rotates about the speed-reduction shaft in the clockwisedirection in FIG. 3, the three planetary gears 137 move around the sungear 138 in the clockwise direction. On the other hand, when the sungear 138 rotates about the speed-reduction shaft in the counterclockwisedirection, the three planetary gears 137 move around the sun gear 138 inthe counterclockwise direction. During this, the rotation of the motor133 is transmitted to the spool 132 while the rotational speed isreduced to some fraction of the rotational speed of the motor and thetorque is increased. By the rotation transmitted to the spool 132, theseatbelt 110 is wound onto or unwound from the outer periphery of thespool 132.

In the seatbelt apparatus 100 having the aforementioned structure, thecontrol of the operation of the motor 133 of the retractor 130 is usedwhen the restraint of the vehicle occupant is conducted or when therestraint of the vehicle occupant is cancelled. The control is suitablyconducted by the ECU 150 based on the input signals from the inputelement 170 shown in FIG. 1. That is, the seatbelt apparatus 100 of thisembodiment has such a function that, based on the input signals from theinput element 170, the ECU 150 controls the operation of the motor 133to adjust the tension of the seatbelt 110 so as to control the conditionabout the restraint of the vehicle occupant and therefore composes anoccupant restraining system for a vehicle. Specifically, the followingfirst through fifth modes may be employed.

In the first mode (putting-on mode), the motor 133 is controlled to berotated in the belt unwinding direction to facilitate the vehicleoccupant to withdraw the seatbelt when the vehicle occupant inserts andlatches the tongue to the buckle of the seatbelt by his or her hand.Accordingly, the load and operation for withdrawing the seatbelt can berelieved.

In the second mode (fitting mode), the motor 133 is controlled to berotated in the belt winding direction to apply predetermined tension onthe seatbelt in the state that the seatbelt is worn by the vehicleoccupant. Accordingly, slack of the seatbelt generated when the seatbeltis withdrawn can be eliminated. If necessary, the motor 133 may becontrolled to rotate a little in the belt winding direction or the beltunwinding direction to conduct fine adjustment for controlling comfortof the vehicle occupant wearing the seatbelt.

In the third mode (pre-rewinding (restraining) mode), the motor 133 iscontrolled to rotate in the belt winding direction to apply strongtension on the seatbelt when the seatbelt is worn by the vehicleoccupant. Accordingly, change in posture of the vehicle occupant due toa vehicle collision or emergency braking is inhibited so as to ensurethe protection of the vehicle occupant.

In the fourth mode (warning mode), when danger or collision is predictedin the state the seatbelt is use d, the motor 133 is controlled torotate in the belt winding direction or the belt unwinding direction tochange tension on the seatbelt so as to urge the vehicle occupant to payattention. For example, the operation of applying strong tension andweak tension onto the seatbelt is repeated, thereby preventing thevehicle occupant from dozing and thus ensuring the collision prevention.

In the fifth mode (storing mode), the motor 133 is controlled to rotatein the belt winding direction to facilitate the vehicle occupant tostore the seatbelt after the vehicle occupant releases the latching ofthe tongue from the buckle. Accordingly, the load and operation forstoring the seatbelt can be relieved.

The present invention is not limited to the aforementioned embodiment,various variations and modifications may be made. For example, thefollowing embodiments as variations of the aforementioned embodiment maybe carried out.

Though the retractor 130 described in the above embodiment is used forthe vehicle occupant seated in the driver's seat and is accommodated inthe accommodating space in the B-pillar, the present invention can beadopted to the structure of retractors for vehicle occupants seated in apassenger's seat and a rear seat. When the present invention is adoptedto the structure of a retractor for a vehicle occupant seated in therear seat, the retractor is accommodated in an accommodating space in aC-pillar in case of an automobile of a type having two rows of seats orthe retractor is accommodated in an accommodating space in a C-pillar ora D-pillar in case of an automobile of a type having three rows ofseats. The accommodating space in the C-pillar or the D-pillar is oftenlimited in the longitudinal direction of the vehicle. Especially in suchcase, a retractor having reduced size in the width direction such as theretractor 130 in the embodiment is effective.

Though the above embodiment has been described with regard to the casethat the retractor 130 is accommodated in the accommodating space in thepillar, the present invention can be adopted to the structure in whichthe retractor is accommodated in an accommodating space in a memberother than the pillar. For example, a vehicle seat such as a driver'sseat or a passenger's seat as a first-row seat, or a seat as a second-or third-row seat may be provided with an accommodating space insidethereof and the retractor 130 of the embodiment can be accommodated inthe accommodating space inside the seat. The size of the seat is oftenlimited in the longitudinal direction of the vehicle similarly to thevehicle pillar. Especially in the case, a retractor having reduced sizein the width direction such as the retractor 130 in the embodiment iseffective.

Though the above embodiment has been described with regard to thestructure of the seatbelt apparatus to be installed in an automobile,the present invention can be adopted to seatbelt apparatus to beinstalled in a wide variety of vehicles other than automobile such asaircraft, boat, and train.

Japan Priority Application 2004-317013, filed Oct. 29, 2004 includingthe specification, drawings, claims and abstract, is incorporated hereinby reference in its entirety.

Given the disclosure of the present invention, one versed in the artwould appreciate that there may be other embodiments and modificationswithin the scope and spirit of the invention. Accordingly, allmodifications attainable by one versed in the art from the presentdisclosure within the scope and spirit of the present invention are tobe included as further embodiments of the present invention. The scopeof the present invention is to be defined as set forth in the followingclaims.

1. A seatbelt retractor comprising: a spool formed into a hollowcylindrical shape and capable of winding a seatbelt onto a spool outerperiphery or unwinding the seatbelt from the spool outer periphery,wherein the seatbelt is adapted to be worn by a vehicle occupant seatedin a seat; a motor accommodated in a hollow space of the spool andconfigured to rotate the spool in the belt winding direction or the beltunwinding direction; a motor speed-reduction mechanism configured toreduce the rotational speed of the motor via a plurality of gearsbetween the driving shaft of the motor and the spool; and a controlmechanism configured to control the operation of the motor, wherein inthe state that the motor is accommodated in the hollow space, a motorhousing of the motor extends along the width direction of the spoolouter periphery of the spool such that the axial direction of the motorcoincides with the width direction of the spool outer periphery, andwherein the length of the motor housing in the axial direction and thewidth of the spool outer periphery are substantially equal.
 2. Theseatbelt retractor as claimed in claim 1, wherein the length of themotor housing in the axial direction and the width of the spool outerperiphery are substantially equal to the width of the seatbelt.
 3. Theseatbelt retractor as claimed in claim 1, wherein the spool and themotor housing are supported by each other via a bearing mechanismdisposed between the inner periphery of the spool and the outerperiphery of the motor housing.
 4. The seatbelt retractor as claimedclaim 1, wherein the seatbelt retractor is adapted to be accommodated inan accommodating space in a rear pillar of a vehicle which is located onthe rear side of an A-pillar of the vehicle.
 5. The seatbelt retractoras claimed in claim 4, wherein in the state that the seatbelt retractoris accommodated in the accommodating space, the spool outer periphery ofthe spool extends in the longitudinal direction of the vehicle, and thelength corresponding to the width of the spool outer periphery and thelength of the accommodating space in the longitudinal direction of thevehicle are substantially equal.
 6. The seatbelt retractor as claimed inclaim 1, wherein the seatbelt retractor is adapted to be accommodated inan accommodating space in a seat of an vehicle.
 7. The seatbeltretractor as claimed in claim 1, wherein a ratio of an outside diameterD1 of the motor housing relative to an outside diameter D2 of the spoolouter periphery is 0.8 or less.
 8. A seatbelt retractor comprising: aspool formed into a hollow cylindrical shape and capable of winding aseatbelt onto a spool outer periphery or unwinding the seatbelt from thespool outer periphery, wherein the seatbelt is adapted to be worn by avehicle occupant seated in a seat; a motor accommodated in a hollowspace of the spool and configured to rotate the spool in the beltwinding direction or the belt unwinding direction; a motorspeed-reduction mechanism configured to reduce the rotational speed ofthe motor via a plurality of gears between the shaft of the motor andthe spool; and a control mechanism configured to control the operationof the motor, wherein in the state that the motor is accommodated in thehollow space, a motor housing of the motor extends along the widthdirection of the spool outer periphery of the spool such that the axialdirection of the motor housing coincides with the width direction of thespool outer periphery, and the motor speed-reduction mechanism isdisposed adjacent to the motor housing relative to the axial directionof the motor housing, and wherein a first length relating to the widthdirection of the spool outer periphery and a second length correspondingto the length of the motor housing in the axial direction plus a lengthof the motor speed-reduction mechanism in the axial direction aresubstantially equal.
 9. The seatbelt retractor as claimed in claim 8,wherein the first length and the second length are substantially equalto the width of the seatbelt.
 10. The seatbelt retractor as claimed inclaim 8, wherein the gears of the motor speed-reduction mechanism arearranged to extend on the same plane perpendicular to the axialdirection of the motor housing.
 11. The seatbelt retractor as claimed inclaim 8, wherein the spool and the motor housing are supported by eachother via a bearing mechanism disposed between the inner periphery ofthe spool and the outer periphery of the motor housing.
 12. The seatbeltretractor as claimed in claim 8, wherein the seatbelt retractor isadapted to be accommodated in an accommodating space in a seat of anvehicle.
 13. The seatbelt retractor as claimed claim 8, wherein theseatbelt retractor is adapted to be accommodated in an accommodatingspace in a rear pillar of a vehicle which is located on the rear side ofan A-pillar of the vehicle.
 14. The seatbelt retractor as claimed inclaim 13, wherein in the state that the seatbelt retractor isaccommodated in the accommodating space, the spool outer periphery ofthe spool extends in the longitudinal direction of the vehicle, and thelength corresponding to the width of the spool outer periphery and thelength of the accommodating space in the longitudinal direction of thevehicle are substantially equal.
 15. A seatbelt apparatus comprising: aseatbelt retractor; and a seatbelt to be worn by a vehicle occupantseated in a seat, wherein the seatbelt retractor comprises: a spoolformed into a hollow cylindrical shape and capable of winding theseatbelt onto a spool outer periphery or unwinding the seatbelt from thespool outer periphery; a motor accommodated in a hollow space of thespool and configured to rotate the spool in the belt winding directionor the belt unwinding direction; a motor speed-reduction mechanismconfigured to reduce the rotational speed of the motor via a pluralityof gears between the driving shaft of the motor and the spool; and acontrol mechanism configured to control the operation of the motor,wherein in the state that the motor is accommodated in the hollow space,a motor housing of the motor extends along the width direction of thespool outer periphery of the spool such that the axial direction of themotor coincides with the width direction of the spool outer periphery,wherein the length of the motor housing in the axial direction and thewidth of the spool outer periphery are substantially equal.
 16. Avehicle with a seatbelt apparatus, wherein the seatbelt apparatus asclaimed in claim 15, is accommodated in an accommodating space in apillar or an accommodating space in a seat.
 17. A seatbelt apparatuscomprising: a seatbelt retractor; and a seatbelt to be worn by a vehicleoccupant seated in a seat, wherein the seatbelt retractor comprises: aspool formed into a hollow cylindrical shape and capable of winding theseatbelt onto a spool outer periphery or unwinding the seatbelt from thespool outer periphery; a motor accommodated in a hollow space of thespool and configured to rotate the spool in the belt winding directionor the belt unwinding direction; a motor speed-reduction mechanismconfigured to reduce the rotational speed of the motor via a pluralityof gears between the shaft of the motor and the spool; and a controlmechanism configured to control the operation of the motor, wherein inthe state that the motor is accommodated in the hollow space, a motorhousing of the motor extends along the width direction of the spoolouter periphery of the spool such that the axial direction of the motorhousing coincides with the width direction of the spool outer periphery,and the motor speed-reduction mechanism is disposed adjacent to themotor housing relative to the axial direction of the motor housing,wherein a first length corresponding to the width of the spool outerperiphery and a second length corresponding to the length of the motorhousing in the axial direction plus a size relating to the axialdirection of the motor speed-reduction mechanism are substantiallyequal.
 18. A vehicle with a seatbelt apparatus, wherein the seatbeltapparatus as claimed in claim 17, is accommodated in an accommodatingspace in a pillar or an accommodating space in a seat.